I use a natural starter, just fermented flour and water. Add the starter to whole wheat flour, water and a pinch of salt. I buy Bob's Red Mill Whole Wheat flour in 50lb sacks. A loaf of bread costs less than a dollar to make. So it's not the cost, it just takes a bit of time and most of that is just waiting for the leavening process to work.

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I bake mine in a Dutch oven. I drop the ball of dough in the Dutch oven in an upside down parachute of parchment paper, then I add a cup of ice to make steam. The parchment paper isolates the dough from the ice. The steam gives the finished loaf a great texture.